Dr. Stewart DVM writes:
Quote:
There is also wide variation in susceptibility to ‘triggering’ factors, which include:
1) genetic muscle disorders
2) vitamin E and/or selenium deficiency
3) delayed muscle soreness from free radical damage
4) hormonal disturbances
5) thyroid disorders
6) electrolyte imbalances
7) diets high in raw grain which can result in carbohydrate overloading
8) viral and bacterial infections
9) abnormal muscle calcium levels
It seems to me that in my experience the below are the most likely culprits in racehorses tying up:
Vit E/Selenium deficiency.............supplement with the two
hormonal disturbances.................supplementing with magnesium
abnormal muscle calcium levels..........supplementing with magnesium may also help
thyroid disorders........................look to supplementing with iodine.
Lastly injecting with Vitamin C and lipoic acid may also be called for to help normalize the system.
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One of the misconceptions with tying up has been that it caused by high muscle
lactic acid concentrations. However, recent research has shown that muscle
lactic acid levels are in fact low in these horses. In addition, few horses tie up
after racing, when muscle and blood lactate levels are at their highest.
Muscle biopsies have shown that it is the Type II or fast twitch fibres which suffer damage in these horses.
Most equine diets are too low in magnesium and the horses with responsive
behavior problems (sensitive to touch/sound, "jumpiness" in general) are
sensitive to the low intake. Magnesium is critical to the normal functioning of an
estimated 350 enzyme systems in the body. It is particularly critical to skeletal
muscle, the nervous system and glucose metabolism. Symptoms of magnesium
deficiency include: muscular symptoms from twitching to high muscle tension to
cramping to spasm; hypersensitive to touch and sound; shying/spooking; anxiety
and nervousness in general; abnormal glucose metabolism.
Magnesium deficiency is also strongly associated with hypertension in humans
and correction of magnesium intake is always part of my approach to a horse that
has bled. Imbalances in the calcium:magnesium ratio are associated with tying
up, especially in fillies and mares when oestrogen influences mineral balance
when they are in season. Magnesium helps a lot of horses who tie up, regardless
of sex.